CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
CONDENSED CONSOLIDATED STATEMENTS OF INCOME (unaudited) [Abstract]
Net sales	$ 54,587	$ 56,311	$ 57,235
Cost of sales	27,844	29,649	33,436
Gross profit	26,743	26,662	23,799
Operating expenses:
Engineering, design and product development	4,576	4,303	4,425
Selling and marketing	7,203	7,561	6,907
General and administrative	8,205	7,984	7,267
Operating expenses	19,984	19,848	18,599
Operating income (loss)	6,759	6,814	5,200
Interest and other income (expense):
Interest expense	(27)	(33)	(33)
Interest income	0	0	7
Other, net	(266)	(9)	(4)
Interest and other expense	(293)	(42)	(30)
Income (loss) before income taxes	6,466	6,772	5,170
Income tax provision (benefit)	1,040	3,561	1,553
Net income (loss)	$ 5,426	$ 3,211	$ 3,617
Net income (loss) per common share:
Basic (in dollars per share)	$ 0.73	$ 0.43	$ 0.48
Diluted (in dollars per share)	$ 0.70	$ 0.42	$ 0.47
Shares used in per-share calculation:
Basic (in shares)	7,444	7,423	7,610
Diluted (in shares)	7,759	7,592	7,655
Dividends declared and paid per common share (in dollars per share)	$ 0.36	$ 0.35	$ 0.32